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133results about How to "Suppress overvoltage" patented technology

Power electronic transformer applied to distribution network

The invention relates to an electric power electronic transformer applied to a distribution network, which is divided into an input level, an isolation level and an output level. The isolation level uses a power converter with a bridge topology structure to adapt to the requirement of different voltage levels of input; the isolation level uses a form that a plurality of high-frequency transformers respectively carry out isolation, transformation and energy transmission; and the output level has two topology structures, wherein the first structure is formed by parallel connection of the power converter with the bridge topology structure, and the second structure is formed by cascade connection of the power converter with the bridge topology structure, and simultaneously an LC wave filter is connected to improve the voltage-current waveform quality. The complete appliance totally uses mature power devices, is formed by combining basic power units and can be flexibly applied to distribution network lines with different voltage levels. The transformer can automatically regulate line output voltage to stably output voltage, thereby inhibiting voltage quality problems of voltage falling, rising as well as flickering, overvoltage, undervoltage and the like.
Owner:SOUTHEAST UNIV

Electric railway section post automatic passing over of neutral section system and control method thereof

The invention discloses an electric railway section post automatic passing over of neutral section system and a control method thereof, and relates to the field of electric railway traction power supply. Pantograph recognizers are arranged on sectionalizers close to power supply arms. Load switches, thyristor switches and current transformers are sequentially connected in series and then connected to the two ends of the sectionalizers in parallel together with resistors and standby switches. The output ends of the pantograph recognizers, the current transformers and a voltage transformer, the trigger ends of the thyristor switches and the operation ends of the load switches and the standby switches are connected with a control unit. After the first thyristor switch is turned off due to current zero, the second thyristor switch is turned on to achieve current zero crossing point instantaneous switching from the first power supply arm to the second power supply arm, so that the power supply of a train is instantaneously switched from the first power supply arm to the second power supply arm, and uninterruptible power supply is achieved. The high-voltage high-resistance first resistor and second resistor work independently or together, and both can restrain balance current and the potential transient process. The system is mainly used for train continuous electricity passing over of neutral section.
Owner:SOUTHWEST JIAOTONG UNIV +1

Direct-current overvoltage current limiting control method of flexible HVDC convertor station

The invention provides a direct-current overvoltage current limiting control method of a flexible HVDC convertor station. The method can solve the problems that when alternating-current side grid faults of a flexible HVDC system receiving end convertor station or direct-current monopole disconnection faults of a sending end convertor station happen, power output of the sending end convertor station is limited so that direct-current bus overvoltage is caused, and when the voltage exceeds a protection setting value, a flexible HVDC system is locked and shut down, and the method can be used for quickly lowering the absorbed active power value of the sending end convertor station from an alternating-current power grid and restraining direct-current circuit voltage rise. When the method is applied to flexible HVDC system control, and power grid faults cause the problems that the convertor station power transmitting capacity is limited and direct-current voltage quickly rises, the absorbed active power of the sending end convertor station from the alternating-current power grid is lowered, direct-current voltage rise is restrained, and the problem that the flexible HVDC system is locked and shut down due to the fact that the voltage exceeds the protection setting value is avoided.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +2

Self-turnoff component driving protection circuit

InactiveCN102723935AImprove securityWaveform is stable and idealElectronic switchingControl signalEngineering
The invention relates to a self-turnoff component driving protection circuit which particularly comprises positive and negative power supplies, an optical coupler isolating circuit, a control circuit, an anti-saturation circuit, a high power transistor and a composite buffer circuit, wherein a control signal current is subjected to resistance-capacitance filtering and is subsequently input into the anode of a primary light emitting diode of the optical coupler component; an emitter electrode of a secondary phototriode of the optical coupler component is directly connected with the input end of a chip UAA4002 in the control circuit; the positive power supply is connected with the collector electrode of the phototriode through a switch; the positive and negative power supplies are respectively connected with positive and negative power supply pins of the chip UAA4002 and are respectively connected with the collector electrodes of subsequent upper and lower pair tubes, the control circuit is connected with the anti-saturation circuit through a current-limiting resistor; the anti-saturation circuit is connected in parallel between the base electrode and the collector electrode of the high power transistor; and the composite buffer circuit is directly connected in parallel between the collector electrode and the emitter electrode of the high power transistor; thereby a self-turnoff component driving protection circuit which is simple in circuit structure, complete in function, high in reliability, small in switch consumption and rapid in protection response is provided.
Owner:柏德胜 +2

Method for MMC type VSC-HVDC system precharge control

The invention discloses a method for MMC type VSC-HVDC system precharge control. The method is based on a CPSM (carrier phase shifted modulation) strategy and controls by adoting a voltage outer ring and a current inner ring, wherein the voltage ring controls capacitor voltage of a sub-module, and the current ring controls three-phase AC current. The method disclosed by the invention gives consideration to the precharge speed and the precharge efficiency while limiting impact current and preventing overvoltage. The control method is clear in thinking, easy in engineering realization, and has good dynamic performance and steady-state performance.
Owner:HUNAN UNIV

Linear approximation solution method of voltage and reactive power optimization of distribution network

The invention, which belongs to the optimization operation field of the power system, discloses a linear approximation solution method of voltage and reactive power optimization of a distribution network. An active distribution network reactive power optimization module is established by using reactive power outputs of a distributed power supply and a discrete reactive power regulating device in a distribution network as state variables and using the operation transmission loss of the distribution network as an objective function; linearization is carried out on an active distribution network reactive power optimization module to obtain a linear approximation model; and alternate iteration is carried out on a loaf flow analysis and the linear approximation model to solve a solution approximating an original non-convex problem. According to the invention, for the distribution network design with loop network operation, the reactive power regulation capability of the distributed power supply can be fully utilized to realize coordinated cooperation with other reactive-load compensation devices; over-voltage and under-voltage problems caused by grid connection of a distributed power supply can be solved; the operation losses of the distribution network can be reduced; the capability of the distribution network for absorbing the distributed power supply can be improved; the safe and economic operation of the distribution network can be guaranteed; and the model solution becomes simple and reliable and no non-feasible solution is generated.
Owner:SOUTHEAST UNIV

Method for inhibiting overvoltage and overcurrent of resonant transformation circuit and resonant transformation circuit

InactiveCN102364850AChanging impedanceSuppresses overvoltage and overcurrent stressEfficient power electronics conversionDc-dc conversionPhysicsCapacitance
The invention discloses a method for inhibiting an overvoltage and an overcurrent of a resonant transformation circuit and the resonant transformation circuit. The resonant transformation circuit comprises an inverter bridge, a transformer, a resonant capacitor, a resonant inductor and a resonant branch circuit connected in parallel with the resonant capacitor. The resonant capacitor, the resonant inductor and a transformer primary winding are connected in series. A series circuit of the resonant capacitor, the resonant inductor and the transformer primary winding is connected with an output end of the inverter bridge. The resonant branch circuit comprises an auxiliary resonant capacitor and a pressure-sensitive device. The auxiliary resonant capacitor is connected in series with the pressure-sensitive device. By dynamically changing parameters of the resonant circuit, a voltage stress and a current stress of the resonant circuit under the abnormal working condition can be effectively reduced and the working reliability of the circuit is improved.
Owner:SHENZHEN MEGMEET ELECTRICAL CO LTD

PWM (pulse width modulation) based monostable vacuum circuit breaker permanent magnetic operating mechanism control method and device for implementing same

The invention relates to a PWM (pulse width modulation) based monostable vacuum circuit breaker permanent magnetic operating mechanism control method and a device for implementing the same. Adjustments are performed through three closed loops including a contact position loop, a contact speed loop and a mechanism coil current loop. Exciting current is adjusted by the contact position loop according to the contact position. A PWM duty cycle is adjusted by the contact speed loop according to feedback signals of the contact position loop. Switch-on-off operations are controlled by the mechanism coil current in real-time according to the exciting current and the PWM duty cycle. A fuzzy PID (proportional integral derivative) controller is adopted in the contact position loop and the contact speed loop. PI (priority interrupt) control is adopted in the mechanism coil current loop. The PWM based monostable vacuum circuit breaker permanent magnetic operating mechanism control method has the advantages that synchronous operation capacity and reliability of the mechanism are improved; the main coil current detection and the auxiliary contact travel detection are cooperated with each other; and a pulse width modulation technology is adopted in operations of a circuit breaker, closed-loop control of contact movement features in the switch-on-off operations of the circuit breaker is realized through changing the coil current, stability of operation time is guaranteed, and accuracy of switch-on-off phases is improved.
Owner:NANJING INTELLIGENT DISTRIBUTION AUTOMATION EQUIP

Power supply apparatus

There is provided a power supply apparatus that is capable of suppressing the occurrence of anomalous electric discharge due to charge-up of a substrate and that is capable of forming a good thin film on a large-area substrate. The power supply apparatus of this invention has: a first discharge circuit that alternately charges predetermined potential at a predetermined frequency to a pair of targets that are in contact with a plasma; and a second discharge circuit that charges predetermined potential between the grounding and the electrode, out of the pair of electrodes, that is not charged with potential from the first discharge circuit. The second discharge circuit is provided with a reverse potential charging means for charging, at the time of polarity reversal, at least one of the electrodes with potential that is reverse to the output potential.
Owner:ULVAC INC

Low-voltage ride through control method and device for doubly-fed wind power generating system

The invention discloses a low-voltage ride through control method and a low-voltage ride through control device for a doubly-fed wind power generating system. The device comprises a reversible power converter, a motor controller, a signal detection circuit and a crowbar protection circuit. The crowbar protection circuit consists of a three-phase uncontrolled bridge rectifier, a primary release circuit and a secondary release circuit. When a power grid has a low-voltage failure, the reversible power converter stops working, the primary and secondary release circuits in the crowbar protection circuit are switched on at the same time and work in parallel to rapidly release transient impact current in a rotor winding of a doubly-fed motor; when the current of a rotor attenuated to a rated value, the secondary release circuit stops working, and the primary release circuit is still switched on to release the transient current in the rotor wining; and after the low-voltage failure of the power grid is eliminated to recover the voltage of the power grid, the reversible power converter restarts working, and the crowbar protection circuit completely stops working. By the method and the device, high ride through capability and good effects are ensured, the time of a transient process for low-voltage ride through can be shortened, the voltage recovery of the power grid can be accelerated and secondary over-current can be effectively prevented.
Owner:CHINA UNIV OF MINING & TECH +1

Inverter circuit and power conversion device

An inverter circuit provided in a power conversion device includes a full-bridge inverter, and a short circuit part. The short circuit part includes switching elements and clamp elements connected to the switching elements. The clamp elements suppress application of an excessive voltage such as a surge voltage to the switching elements.
Owner:ORMON CORP

Removing method and control apparatus for alternating current filters for high-voltage direct-current power transmission

The invention discloses a removing method and a control apparatus for alternating current filters for high-voltage direct-current power transmission. A constant value of the total number of the alternating current filters which need to be removed is set according to requirements of alternating current voltage and reactive power; the input alternating current filters are divided into two conditions, including the alternating current filters which participate in the filtering function and the alternating current filters which do not participate in the filtering function; the number of groups of the various kinds of equivalent removing filters of the alternating current filters which participate in the filtering function is determined according to the minimum filter configuration table; if the number of the groups of the alternating current filters which do not participate in the filtering function is greater than or equal to the constant value of the total number of the alternating current filters which need to be removed, only the alternating current filters which do not participate in the filtering function are removed; or otherwise, the alternating current filters which do not participate in the filtering function, and the alternating current filters which participate in the filtering function in the residual groups are removed; when the alternating current filters which participate in the filtering function are removed, the number of the removing groups of each type is calculated according to the filtering performance; the alternating current filters are removed in sequence rapidly; and therefore, the overvoltage of the alternating current power grid can be effectively restrained, or the reactive power requirement can be rapidly satisfied.
Owner:NR ELECTRIC CO LTD +1

Power conversion device

ActiveUS20170264225A1Suppress overvoltageOccurrence of overvoltage due to a LC resonance phenomenon can be reliably suppressedVector control systemsDynamo-electric converter controlEngineeringVoltage
A power conversion device includes a high-pass filter for extracting an AC component of voltage Vdc of a DC link section, a multiplier for multiplying output VdcAC of the high-pass filter by a first gain K1 and outputting the result, a multiplier for multiplying output of the multiplier by a second gain K2 and outputting the result as a d-axis voltage correction signal vdcmp*, and a multiplier for multiplying output of the multiplier by a third gain K3 and outputting the result as a q-axis voltage correction signal vqcmp*. The gate signal generation section generates gate signals on the basis of a signal vd1 obtained by adding the d-axis voltage correction signal vdcmp* to a d-axis voltage command value vd* and a signal vq1 obtained by adding the q-axis voltage correction signal vqcmp* to a q-axis voltage command value vq*.
Owner:MITSUBISHI ELECTRIC CORP

High-reliability thermal-protection piezoresistor

InactiveCN104485188ASuppress overvoltageWide range of breakaway currentVaristorsEngineeringElectric devices
The invention relates to a high-reliability thermal-protection piezoresistor. An overheating separation node is arranged at each of two surfaces of a resistor disc, and the positions of the nodes are selected properly, so that the current separation range of the piezoresistor is wide from several mA to 100A, the separation speed is high and is faster than that of most of existing products under large current by 10 times, the safety is good, and the firing is avoided; the piezoresistor can be used independently and also can be used as a chip of a surge protection device (SPD) for preventing lightning overvoltage, operation overvoltage and other surge overvoltage, so that the electrical and electric devices and equipment are protected; when the piezoresistor is used in a use circuit, a fuse protector or an air switch for preventing the short circuit of an upstream piezoresistor can be omitted.
Owner:常州市天泰电路保护技术有限公司

Neutral-point grounding control equipment medium-voltage power grid

The invention discloses neutral-point grounding control equipment of a medium-voltage power grid. The neutral-point grounding control equipment comprises a bus voltage transformer, a grounding transformer, a circuit zero-sequence current transformer and a controller, wherein the bus voltage transformer is connected with a bus and the controller, the grounding transformer is connected with the busand an arc extinguishing coil, a neutral point current transformer and a neutral point voltage transformer are arranged between the grounding transformer and the arc extinguishing coil and are connected with the controller, a branch is arranged between the neutral voltage transformer and the arc extinguishing coil and is connected with a resistor by a switch connected with the controller, the controller is connected with at least two branch lines by the circuit zero-sequence current transformer, and the branch lies are connected with the bus. The advantages of two grounding modes of neutral-point resonant grounding and resistance grounding are combined, the advantage that a line can be accurately selected by resistance grounding is maintained, residual current of a grounding point also canbe reduced, an arc light grounding overvoltage is limited, an appropriate working mode can be selected according to different conditions of a short-term grounding fault or a permanent grounding fault, the safety running of the line is guaranteed, and the power supply reliability is also improved.
Owner:赵子云 +1

Over-voltage protection method achieved by adoption of dry-type air-core shunt reactor combined over-voltage protection circuit

The invention provides an over-voltage protection method achieved by the adoption of a dry-type air-core shunt reactor combined over-voltage protection circuit and belongs to the field of reactor over-voltage protection. The problems that an existing dry-type air-core shunt reactor combined over-voltage protection device recrudesces and is poor in over-voltage protection effect are solved. The cut-off current over-voltage protection is performed as follows, when a switch K of a circuit breaker is cut-off, cut-off current over-voltage occurs, i0 is set as a power frequency cut-off current value, U0 is set as a reactor power frequency voltage peak value, when t=0, the circuit breaker generates cut-off current, a resistance-capacitance protection device works, when the voltage on a protection device absorption capacitor C is not larger than the residual voltage of a lightning arrester, the resistance-capacitance protection device directly completes the cut-off current over-voltage protection on the reactor, when t=t0, the voltage on the protection device absorption capacitor C is larger than the residual voltage U1 of the lightning arrester, the lightning arrester makes action, when t=t1, the voltage on the protection device absorption capacitor C is less than or equal to the residual voltage U1 of the lightning arrester, the lightning arrester exits action, and the resistance-capacitance protection device continues to complete the cut-off current over-voltage protection on the reactor. The over-voltage protection method achieved by the adoption of the dry-type air-core shunt reactor combined over-voltage protection circuit is mainly used for reactors.
Owner:STATE GRID CORP OF CHINA +2

Lightning arrester

The invention relates to the field of a power system, and discloses a lightning arrester. The lightning arrester comprises an arc extinguishing segment and a resistance segment, wherein the arc extinguishing segment and the resistance segment are coaxially and vertically arranged, an upper end of the arc extinguishing segment is connected with a lower end of the resistance segment, an upper end of the resistance segment is connected with external ground, the arc extinguishing segment comprises an epoxy core rod and a spiral umbrella disc, the spiral umbrella disc is spirally wound around an outer side of the epoxy core rod, a plurality of arc extinguishing units are arranged at an outer edge of the spiral umbrella disc at intervals, the resistance segment comprises a cylindrical resistance body and a plurality of annular umbrella discs, the annular umbrella discs are sleeved at an outer side of the resistance body at intervals. By the lightning arrester, a lightning current is effectively released during lightning of a power transmission line, the current amplitude of a power frequency follow current after action of a lightning wave also can be limited, a circuit is prevented from being stricken, the power frequency follow current also can be effectively cut off even the resistance segment is damaged or failure, and the normal and stable running of the power transmission line is ensured.
Owner:STATE GRID HUNAN ELECTRIC POWER +3

Suppression method for fixed time sliding mode of ferromagnetic resonance overvoltage chaos

The invention discloses a suppression method for a fixed time sliding mode of ferromagnetic resonance overvoltage chaos. The method includes the following steps: : (1) establishing a mathematical model of a ferromagnetic resonance system; (2) designing an integral sliding mode surface according to a fixed time stability theory; (3) obtaining a nonlinear control law and an adaptive law of uncertainparameters by theoretical derivation; (4) determining an upper bound of a stable time range according to related lemmas of the fixed time stability theory and Lyapunov function stability analysis; and (5) verifying a control effect by numerical simulation. The disclosed suppression method of a ferromagnetic resonance overvoltage can not only make the system stabilize in a finite time without depending on an initial value, but also enables the upper bound of the stabilization time to be obtained by calculation, has the characteristics of stronger robustness and interference resistance capability, can achieve global uniform asymptotic stability of the system within a predetermined time under any initial conditions, enables the ferromagnetic resonance overvoltage of an electric power systemto be more effectively suppressed, and enables the stability of the electric power system to be improved.
Owner:CHINA UNIV OF MINING & TECH

Reactive power compensation device

The invention discloses a reactive power compensation device, and relates to the field of reactive power compensation. The reactive power compensation device comprises a controller, a synchronizing signal detection circuit, a thyristor, a non-power consumption switch, a capacitor, a magnetic latching relay, a close shutoff detection circuit and a reactor; the controller is connected with the synchronizing signal detection circuit, the thyristor, the non-power consumption switch, the magnetic latching relay and the close shutoff detection circuit; the thyristor is in a parallel connection withthe non-power consumption switch; the thyristor is connected with the capacitor through the reactor; the magnetic latching relay is connected with the thyristor; and according to the synchronizing signal detected by the synchronizing signal detection circuit and the close or shutoff time of the magnetic latching relay detected by the lose shutoff detection circuit, the controller acquires a comparative result and rectifies the drive time of the magnetic latching relay according to the comparative result. The reactive power compensation device provided by the invention can effectively restrainthe high frequency flow and the overvoltage; when the device runs for a long time, the capacitor can be connected at the passing zero time of the voltage or disconnected at the passing zero time of the current; and thus, the service life of the magnetic latching relay and the capacitor is prolonged.
Owner:NORTHEAST AGRICULTURAL UNIVERSITY

Over-voltage suppression apparatus

An overvoltage suppression device which suppresses overvoltage that occurs when breakers which turn on / off the connection between a power source bus and a power transmission line, are turned on after the breakers are turned off. The overvoltage suppression device measures the waveform of voltage on the side of the power source and the voltage on the side of the power transmission line, and extracts the waveform of a component in a predetermined frequency band on the basis of the waveform obtained by multiplying the wave shape of the voltage on the side of the power source by the waveform of the voltage on the side of the power transmission line. The breakers are turned on on the basis of a cycle wherein the waveform is peaked.
Owner:KK TOSHIBA

External electric supply controllable reactor

ActiveCN1933054ARealize automatic dynamic compensationSuppress system overvoltage and sneak supply currentTransformers/inductances coils/windings/connectionsConversion without intermediate conversion to dcMagnetic coreTesting equipment
A controllable reactor with outside electrical source has main body and is made up by oil box, magnetic core pole inside of it, left and right side magnet yokes, up and down magnet yokes, winding of magnetic core pole and all kinds of sensor for detecting all species of parameters. It relates to rectifying and filtering equipment, detecting equipment for detecting electrical network parameter and control unit. The net-side winding, compensate winding and control winding set on the magnetic core pole from outside to inside. Net-side winding connects with transmit electricity circuitry, rectifying and filtering equipment connects with outside alternating current source, one end of control winding connects with input end of rectifying and filtering equipment, its output end connects with the other end of control winding to make up of feedback loops. The control unit joints with end boxes to main body connecting with all kinds of sensor signal, rectifying and filtering equipment and detecting equipment. Detecting equipment connects with transmit electricity circuitry and changes reactance value and capability of reactor by changing saturation and magnetic ratio of iron core.
Owner:TBEA SHENYANG TRANSFORMER GRP CO LTD

Driving circuit for dynamic variable IGBT switching characteristics and protection method thereof

Provided are a driving circuit for dynamic variable IGBT switching characteristics and a protection method thereof. The driving circuit for dynamic variable IGBT switching characteristics includes a pulse distribution and digital control chip, switch arrays and gate driving resistance arrays; the pulse distribution and digital control chip is connected with the input end of an IGBT upper bridge arm through a part of the switch arrays and a part of the gate driving resistance arrays, and connected with the input end of an IGBT lower bridge arm through the rest switch arrays and the rest gate driving resistance arrays; the pulse distribution and digital control chip receives the control pulse signals of a controller, receives status information fed back by the IGBT upper bridge arm and the IGBT lower bridge arm, outputs control pulse to drive the IGBT upper bridge arm and the IGBT lower bridge arm after completing pulse distribution, pulse self-locking, pulse interlocking and other treatments according to the control pulse signals and the status information, and meanwhile controls the switch arrays to dynamically change gate driving resistances. The switching characteristics are optimized, the switching loss is reduced, and besides, malfunction coding can be fed back to the controller so as to facilitate intelligent malfunction diagnosis.
Owner:CHINA ACADEMY OF RAILWAY SCI CORP LTD +2

Tripping logic simulating method for alternating current filters of direct-current converting station

The present invention provides a tripping logic simulating method for alternating-current filters of a direct-current converting station. A simulated loop model automatically cuts off a group of alternating-current filters according the voltage and the lasting time of an alternating-current bus of the current converting station; the alternating-current voltage of the alternating-current bus in the loop is adopted as an input parameter; the constant values of different over-voltage protection sections are compared through a plurality of comparative loop modules; an 'OR' gate outputs '1' or '0' level signals; after '1' signals are output when any constant-value condition of the protection section is met, a certain of delay requirements of relevant action are met, and one small group of alternating-current filters can be cut off, so that the over voltage of the alternating-current bus can be reduced; a plurality of small groups of alternating-current filters are continuously and successively cut off till the alternating-current voltage of the current converting station is lowered to a required value, so that the over voltage of the alternating-current bus is inhibited, and the safe running of a direct-current system is guaranteed.
Owner:CHINA XD ELECTRIC CO LTD

Three-level high-voltage and large-power water-cooling frequency converter system

The present invention relates to a three-level high-voltage and large-power water-cooling frequency converter system. The system comprises a full-digital regulation cabinet, frequency converter cabinets based on dual-bridge arm power units and a water circulation heat radiation system cabinet which are subjected to assembling and combined cabinet to one another from left to right to form a whole set of high-voltage and large-power water-cooling frequency converter system, wherein an exciting winding cabinet employs a three-phase six pulse rectifier to achieve a regulation function of a synchronous machine motor rotor exciting current; the full-digital regulation cabinet employs a DSP+FPGA structure vector controller and takes a 32-bit digital model processor as a core; the bridge arm parallel frequency converter cabinets employ a topology structure mode of unit module parallel and bridge arm parallel, and the whole machine power of the frequency converter is developed through adoptionof modes such as parallel of left and right bridge arms in the dual-bridge arm power unit module, parallel of dual-bridge arm power unit modules or parallel of frequency converter cabinets based on the dual-bridge arm power unit. The three-level high-voltage and large-power water-cooling frequency converter system can effectively achieve rapid installation and maintenance, and can achieve two or more than two times output power of the whole frequency converter on the basis of the current technology volume.
Owner:CHAJNA MAJNING DRAJVS EHND AUTOMEHJSHN KO

Peak closing method for reactive compensation capacitor bank

The invention provides a peak closing method for a reactive compensation capacitor bank and belongs to the field of power quality of electrical power systems. According to the peak closing method for the reactive compensation capacitor bank, the optimum closing phase positions of all phases of capacitor banks are designed according to the fact that the capacitor banks are connected in parallel in the mode that the star-shaped neutral points are grounded or not grounded, the minimum delay time required from the moment a closing signal is received to the moment the on-off action is triggered is calculated according to the intrinsic closing time of a switch and external factors, and thus the capacitor bank is applied to a power grid when both the value of the voltage of the capacitor bank and the value of the voltage of a power grid are peak values. Compared with other closing methods, the peak closing method for the reactive compensation capacitor bank has the advantages that the voltage change ratio is lowered under the same closing time deviation condition, rush current and overvoltage which are generated during closing of the capacitor bank are reduced, power quality is improved, and the peak closing method has an extremely good application prospect on the occasion that reactive compensation is conducted by means of the capacitor bank.
Owner:SHANDONG UNIV OF TECH

Protection connection structure for preventing components in variable frequency power cabinet from flashover impact of tested object

A protection connection structure for preventing components in a variable frequency power cabinet from a flashover impact of a tested object is characterized in that a high-voltage resonance circuit common end G1 (including an exciting transformer high voltage tail and a load capacitor ground terminal), a resonance loop secondary common end and protective common end G2 (including a variable frequency power cabinet housing, an exciting transformer housing, a vehicle body ground terminal and a voltage divider ground terminal), and a control loop common end G3 which are in a loop in the variable frequency power cabinet are connected to the ground independently, a resistance-capacitance absorption device and a lightning arrester are additionally mounted between phases of a variable frequency power supply in the variable frequency power cabinet and between a phase and the ground respectively and are used for absorbing and inhibiting overvoltage, and a lightning arrester is additionally mounted on a high-voltage winding of the exciting transformer, so as to prevent an instant overvoltage generated by breakdown of the tested object from being coupled to a low voltage side.
Owner:STATE GRID CORP OF CHINA +1

Intelligent capacitor capable of realizing on-site zero-crossing switching correction

The invention belongs to the technical field of reactive compensation equipment, and especially relates to an intelligent capacitor capable of realizing on-site zero-crossing switching correction. The intelligent capacitor is composed of a liquid crystal display module, a button operation module, a voltage transformer, a synchronous signal generation module, a microcontroller, a magnetic latching relay driving module, on-off detection module and a main circuit. The microcontroller completes the setting of a zero-crossing switching correction function by means of the liquid crystal display module and the button operation module. The microcontroller detects a synchronous signal of a phase voltage. The on-off detection module detects the on-off state of the main circuit and generates a feedback signal, and the feedback signal is input into the microcontroller. The microcontroller modifies a driving time after judging a zero-crossing time deviation, and zero-crossing capacitance switching of the intelligent capacitor is ensured. According to the invention, a user corrects the zero-crossing switching time on site, the inrush current and the overvoltage are inhibited, and the service lifetime of the intelligent capacitor is improved.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Power conversion device using matrix converter

There is provided a power conversion device using a matrix converter capable of reducing the size and weight of the LC filter which should be arranged at the input stage. N matrix converters are connected to a common LC filter. The N matrix converters operate a common load. In this case, a phase difference of the triangular wave signal (carrier signal) used for generating each matrix converter instruction value is set to 360 degrees / N and the common load is driven with the same frequency so that synchronized operation is performed. Thus, it is possible to obtain frequency of the current flowing into the LC filter which is the triangular wave signal(carrier signal) multiplied by N, thereby reducing the load on the LC filter.
Owner:HITACHI LTD

Method for suppressing overvoltage between current converter bridges and system thereof

The invention relates to a method for suppressing overvoltage between current converter bridges and a system thereof. A widely applied 12-pulse series-structured current converter structure is arranged in an ultrahigh voltage direct current project. In the unlocking process of the actual project, the trigger angle of a 12-pulse valve group probably has deviation, 24 times of harmonic wave is excited, and resonance is caused in a current converter loop by the 24 times of harmonic wave and relatively high overvoltage is generated between the current converter bridges. The size of overvoltage between the current converter bridges is detected firstly and compared with the set threshold value. If the size of overvoltage is greater than the set threshold value, a direct current filter is enabled to be disconnected before unlocking of the current converters next time, the loop of the 24 harmonic wave in the current converters is cut off and generation of overvoltage between the current converter bridges is suppressed. The method is effective, simple and convenient, normal unlocking is performed by overvoltage is suppressed and degree of complexity of a direct current power transmission system is not increased.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD

Method for coordination control of controllable shunt reactors

The invention discloses a method for coordination control of controllable shunt reactors. The method comprises the steps that a controllable shunt reactor control system submits the controllable shunt reactor lifting capacity to a master safety control station device through a home-station safety control substation device; when the master safety control station detects that line tripping occurs on a power transmission channel and the channel tide is larger than a certain value before the accident, the master safety control station sends information to the controllable shunt reactor control system through each safety control substation and locks the original control logic; the safety control substations collect the busbar voltage of each station after the accident and submit the voltages to the master safety control station, the master safety control station makes a decision in a centralized mode, and a command is given to put into part of capacity into the controllable shunt reactors according to the timing sequence if overvoltage is detected; the controllable shunt reactor control system receives and executes the command of adjusting the capacity; the original control logic of the controllable shunt reactor control system is open after a period of time. By the adoption of the method, coordination control of multiple sets of dynamic reactive power compensation equipment distributed in multiple transformer substations can be realized, overvoltage can be effectively restrained after the accident, and system voltage collapse caused by simultaneous incoordinate actions of multiple sets of controllable shunt reactors can be avoided.
Owner:NR ELECTRIC CO LTD +4
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